1. Field of the Invention
The present invention relates generally to vacuum pad devices used in vacuum transport systems and, more particularly, to a vacuum pad device which is configured such that a suction pad is rotated using a ball joint to easily cope with different surface angles of an object.
2. Description of the Related Art
Generally, vacuum transport systems form negative pressure in a pad device using a vacuum pump which uses compressed air, and holds an object using the pad device to which the negative pressure is applied, and then transports the object to a desired place.
The pad device used in these vacuum transport systems typically includes a rigid body and a flexible suction pad. The rigid body is generally connected to a suction port of a vacuum pump, and the suction pad is fixed to the end of the rigid body. When compressed air passes through the vacuum pump, air which has been in the suction pad is drawn into the vacuum pump and then the air, along with the compressed air, is discharged out of the vacuum pump. Thereby, negative pressure is formed in the suction pad.
However, in this conventional structure, because the suction pad is fixed to the end of the rigid body such that the axis of the suction pad is parallel to the axis of the rigid body, the surface under suction that is in contact with the suction pad is always perpendicular to the rigid body. Therefore, if the surface of an object is not perpendicular to the axis of the rigid body, the suction pad cannot directly cope with the inclined surface of the object.
In an effort to overcome the above problem, a pad device was proposed, in which a bellows pipe or a ball joint is provided between a rigid body and a suction pad.
In this structure, the suction pad is rotatably coupled to the rigid body by the bellows pipe or the ball joint. Therefore, the suction contact surface of the suction pad can be oriented in a variety of directions and angles relative to the rigid body, rather than being limited to the perpendicular state.
In other words, the suction pad can freely rotate with respect to the rigid body because of the bellows pipe or the ball joint. Therefore, the suction pad can immediately cope with even an inclined surface of the object that is not perpendicular to the longitudinal axis of the rigid body. That is, when the suction pad is attached to the inclined surface of the object, the suction pad is bent with respect to the rigid body at an angle and in a direction corresponding to the inclined surface.
However, when the suction pad which has been attached to the object lifts the object to transport it to a desired place, the suction pad is rotated by the load of the object. Hence, precisely and safely transporting the object to the desired place becomes very difficult.
To reliably realize application, installation, loading, etc. of the object, conditions, such as the orientation, angle, arrangement, etc. of the object before it is transported should be maintained not only when it is being transported but also after having been transported. However, when and if the suction pad is rotated when being transported, the orientation, angle, etc. of the object are changed during the transportation, and thus the above-mentioned requirements are not met.
Moreover, if the object rotates when being transported, the object may become detached from the suction pad because of the load of the object and the rotational force applied thereto.